The 2015 Paris Agreement, meant to constrain global warming to 1.5 degrees Celsius above pre-industrial levels, has already been breached, according to European scientists who found that last summer was Earth's hottest in the past 2,000 years across the Northern Hemisphere.
More specifically, the new estimates, derived from tree ring records, show the summer of 2023 was 2.07 degrees Celsius warmer than pre-industrial levels — which means the world warmed beyond previous estimates, which placed the quantity at 1.48 degrees Celsius above pre-industrial levels. Comparatively sparse data about the Southern Hemisphere, which responds differently to climate change than its northern counterpart, makes it difficult to draw conclusions about that region's climate over the past two thousand years, the scientists say, which is why their study focuses on the Northern Hemisphere.
